Geochemistry of the metavolcanics of the Hutti-Maski schist belt, south India: Implications to gold metallogeny in the eastern Dharwar craton

The Hutti-Maski schist belt in the eastern Dharwar craton consists predominantly of mafic metavolcanics metamorphosed to amphibolite facies. The amphibolites are tholeiitic in composition with higher abundances of iron and with flat to LREE enriched rare earth patterns. Modelling of major and trace elements suggests that the tholeiitic protoliths were formed from melt enriched mantle sources by different extents of partial melting at pressures similar to 25 kbars. The most common mafic metavolcanics in the three auriferous schist belts of eastern Dharwar craton such as the Kolar, the Ramagiri and the Hutti belts are high-iron tholeiites with LREE enriched rare earth patterns. The gold mineralization in the form of quartz-carbonate veins in the three belts is commonly hosted in high iron-tholeiitic protoliths. The process of formation of Fe-rich tholeiites, their metamorphism to amphibolites and their subsequent emplacement along terrane boundaries could have provided a favourable geochemical environment for gold mineralization.